One of the techniques presently employed to interconnect the dice to the substrate carriers in surface mount devices with the active surfaces of the dice facing away from the substrate carriers is to employ a wire bonding connection. This system of interconnect, particularly in miniature packages, has limitations with respect to both thermal and electrical performance. The wire bonding system also inherently provides a thicker package than what is sometimes desirable and requires a more complicated and involved manufacturing process than, for example, what would be involved with an interconnection employing electrical conducting substrate carrier bumps and chip pads. The lack of leads in the wire bonding system makes for difficulty in testing and inspection and hence in the reliability characteristics of the integrated circuit device assembly.
In addition, in the case of very small surface mount dice, i.e. high pin count density or high number of I/O terminals for small die area manufacturing, cost becomes a concern when utilizing the wire bonding interconnection technique. Another concern present in the employment of the wire bonding system is the limitation imposed with respect to the die/footprint ratio which is inherent relatively small.